This invention relates to a methods of improving the tumor to non-tumor ratio of cytotoxic targeting agents in the treatment of disseminated carcinomas, in particular ovarian carcinomas, by reducing the concentration of the cytotoxic medical agent in the blood circulation after intraperitoneal administration of a cytotoxic agent and thereby facilitating a higher dosage and thereby a more effective treatment regime without exposing the vital organs to higher toxicity.
Among the various methods presented in this invention, means of extracorporeal removal of the circulating toxic agents is particularly attractive.
Ovarian cancer is the sixth most common cancer among women, excluding non-melanoma skin cancers. The American Cancer Society estimates that about 23,100 new cases of ovarian cancer will be diagnosed in the United States during 2000. Ovarian cancer accounts for 4% of all cancers in women.
Ovarian cancer is also the fifth most common cause of cancer deaths among women, causing more deaths than any other cancer of the female reproductive system. It is estimated that there will be about 14,000 deaths from ovarian cancer in the United States during 2000. About 78% of ovarian cancer patients survive one year after diagnosis and over 50% survive longer than five years after diagnosis. If diagnosed, and treated while the cancer has not spread outside the ovary, the five-year survival rate is 95%. However, only 25% of all ovarian cancers are found at this early stage.
The 5-year survival rate refers to the percent of patients who survive at least 5 years after their cancer is diagnosed. Five-year relative survival rates exclude from the calculations patients dying of other diseases, and are considered to be a more accurate way to describe the prognosis for patients with a particular type and stage of cancer. Of course, 5-year survival rates are based on patients diagnosed and initially treated more than 5 years ago. Improvements in treatment often result in a more favorable outlook for recently diagnosed patients.
There are many types of tumors that can start growing in the ovaries. Some are benign (non-cancerous) and never spread beyond the ovary. These patients can be cured by surgically removing one ovary or the part of an ovary containing the tumor. Other types of ovarian tumors are malignant (cancerous) and may spread to other parts of the body.
In general, ovarian tumors are named according to the kind of cells the tumor started from and whether the tumor is benign or cancerous. There are three main types of ovarian tumors. Epithelial tumors start from the cells that cover the outer surface of the ovary. Cancerous epithelial tumors are called carcinomas. Germ cell tumors start from the cells that produce the eggs (ova). Stromal tumors start from connective tissue cells that hold the ovary together and produce the female hormones, oestrogen and progesterone.
Epithelial ovarian carcinomas (EOC) accounts for 85%-90% of ovarian cancers. The cells of EOC may have several forms that can be recognized under the microscope. In addition to their classification by cell type, EOCs are also given a grade and a stage. The grade is on a scale of 1, 2, or 3. Grade 1 EOC more closely resembles normal tissue and tends to have a better prognosis. Grade 3 EOC less closely resembles normal tissues and usually has a worse outlook. The tumor stage describes how far the tumor has spread from where it started in the ovary.
Effective therapeutic methods for the treatment of ovarian cancer have been subjected to intensive research. Most women suffering from ovarian carcinomas die of loco-regional recurrence and peritoneal dissemination; hence, regional therapy has been the main focus for some time. Experience with intraperitoneal therapy of this tumor using conventional chemotherapy agents (Howel S. et. al. Intraperitoneal cisplatinum-based chemotherapy for ovarian carcinoma, Semin. Oncol. 1991,18 (Suppl 3), 5-10); radioactive colloids (Rosenhein N. B. et. al. Radiocolloids in the treatment of ovarian cancer, Obstet Gynecol Surv 1997, 34, 708-20); immunoadjuvants (Bast R. C. et. al. Intraperitoneal immunotherapy of human ovarian carcinoma with corynebacterium parvum. Cancer Res. 1983, 43, 1395-1401); cytokines (Navoli M. et. al. Intraperitoneal recombinant alpha-2-interferon alternating with cisplatin as salvage therapy for minimal residual-disease ovarian cancer: a phase II study. J. Clin. Oncol 1990, 8(6), 1036-1041) have been reported.
Another area of investigation involves treatment with very high doses of anticancer drugs, and then xe2x80x9crescuingxe2x80x9d the woman from the side effects with infusions of her own bone marrow stem cells or peripheral blood stems cells (immature blood cells that may be taken from the bone marrow or removed from the bloodstream by using a special filtering process). The bone marrow or peripheral blood stem cells are removed before a high dose of chemotherapy is administered and is returned to the woman (reinfused) after the high-dose treatment is complete. In that way, the side effect of suppressed blood cell production is overcome. This is an extremely high-risk, experimental procedure because, for the time, the woman is without her normal supply of blood cells and is very vulnerable to infection.
Targeting biomolecules such as tumor specific monoclonal antibodies are widely used in the treatment of haematological cancer diseases and more recently in the treatment of disseminated solid tumors (Breitz H. B. et. al. Radioimmunotherapy of Solid Tumours, in Radioimmunotherapy of Cancer, eds. P. G. Abrams and A. R. Fritzberg, Marcel Dekker, Inc., New York, 2000, p.265-306).
A number of tumor specific monoclonal antibodies and immunoconjugates, suitable for in vivo diagnosis and treatment of ovarian cancer, have been described in U.S. Pat. No. 4,958,009 (Anti-human ovarian cancer immunotoxins and methods of use thereof), in U.S. Pat. No.5,817,313 (Monoclonal antibodies and conjugates thereof useful for the treatment of cancer), in U.S. Pat. No. 5,804,187 (Modified antibodies with human milk fat globule specificity) and in U.S. Pat. No. 5,650,291 (Monoclonal antibodies against an antigen associated with ovarian cervical and other tumors).
Over the past decade a number of clinical studies using intraperitoneal (i.p.) radioimmunotherapy in ovarian cancer have been reported. Various types of monoclonal antibodies including HMFG-1, HMFG-2, AUA-1 and H 17E2 have been labelled with I-131, Y-90 and Re-186, and injected into the peritoneal cavity through peritoneal dialysis catheter under local anaesthesia in volumes ranging from 1-2 liter of normal saline and a specific activity of 4-8 mCi/mg antibody.
The effective dose for i.p. I-131 labelled antibodies is thought to be 150 mCi and the mean peak radioactivity in serum is at 44 hrs, corresponding to 26% of the total injected dose. Most of the radioactivity given (80%) is found as free iodine in the urine. However, when Y-90 labelled antibodies are used, the mean peak of radioactivity in serum is 23%, and only 8-11% of the injected dose is released in the urine after 72 hrs (Rosenblum M. G. et. al. Clinical pharmacology, metabolism and tissue distribution of Y-90-labelled monoclonal antibody B27.3 after intraperitoneal administration. J. Natl. Cancer Inst. 1991 (83) 1629).
Although, toxic exposure to the peritoneum and its close surrounding is usually well tolerated and is 4-70-fold more advantageous than the i.v. route for targeting of peritoneal tumor sites (Ward, B. G. et. al. Localization of radio iodine conjugated to the monoclonal antibody HMFG-2 in human ovarian carcinoma: assessment of intravenous and intraperitoneal routes of administration. Cancer Res. 1987 (47) 4719; Ward B. G. et. al. Radiolabelled monoclonal antibodies in oncology. III Radioimmunotherapy. Nucl. Med. Commun. 1991 (12) 333), a high percentage of the injected activity still localizes in normal tissues; the dose-limiting organ being the bone marrow. Myelosuppression arises 4-6 weeks after the initial injection. Grade 3 platelet and granulocyte toxicity (according to the WHO standard) was observed at a total dose of 20 mCi with Y-90 labelled antibody and 160 mCi with I-131 (Stewart J. S. et. al. Intraperitoneal I-131 and Y-90 labelled monoclonal antibodies for ovarian cancer: pharmacokinetics and normal tissue dosiometry. Int. J. Cancer 1988 (3 suppl.), 71; Stewart J. S. et. al. Intraperitoneal yttrium-90 labelled monoclonal antibody in ovarian cancer. J. Clin. Oncol. 1990, (8), 1941; Maraveyas A. et. al. Pharmacokinetics and toxicity of an yttrium-90-CITC-DTPA-HMFG-1 radioimmunoconjugate for intraperitoneal radioimmunotherapy of ovarian cancer. Cancer 1993 (73) 1067), while grade 3 and 4 haematological toxicity was observed at a total dose of 150 mCi with Re-186 (Jacobs A. J. et. al. A phase I trial of a rhenium 186-labeled monoclonal antibody administered intraperitoneally in ovarian cancer carcinoma: toxicity and clinical response. Obstet. Gynecol. 1993 (82) 586).
From the review of the relevant clinical trials, it is clear that i.p. radioimmunotherapy is of benefit mainly to patients with small-volume disease. All studies performed agree that patients with lesions  less than 2 cm have a prolonged disease-free period when compared with historical control group (Hird et. al. Adjuvant therapy of ovarian cancer with radioactive monoclonal antibody. Br. J. Cancer 1993 (82) 586). In the same group of patients, tumor regression has been reported for a number of cases (Epenetos A. A. et. al. Antibody guided irradiation of malignant lesions: three cases illustrating a new method of treatment. Lancet 1984, 1441; Maraveyas A. et. al. Pharmacokinetics and toxicity of an yttrium-90-CITC-DTPA-HMFG-1 radioimmunoconjugate for intraperitoneal radioimmunotherapy of ovarian cancer. Cancer 1993 (73) 1067) as well as decrease in tumor size (Jacobs A. J. et. al. A phase I trial of a rhenium 186-labeled monoclonal antibody administered intraperitoneally in ovarian cancer carcinoma: toxicity and clinical response. Obstet. Gynecol. 1993 (82) 586).
However, the results are rather poor in patients with nodules  greater than 2 cm in diameter subjected to radioactive doses at, or close to, the maximum tolerated dose, since too little of the radioactive antibodies are penetrating the tumorous tissue and the high-energy radiation reaches the limit of its distant killing effect (Ward B. et. al. The treatment of intraperitoneal malignant disease with monoclonal antibody guided 131-I radiotherapy. Br. J. Cancer 1988 (58) 658). This group of patients number more than 50% of patients in need of treatment. Thus, the dose necessary to reach an effective therapy in this group of patients is hampered by the accumulation of radioactivity in the blood circulation, leading to toxicity of normal organs, notably the bone marrow.
Other carcinomas where intraperitoneal administration of cytotoxic medical agent could be applicable, either alone, or in combination with intravenous administration, includes, but is not limited to, colon and/or rectal cancer.
Most medical agents, and in particular larger molecules, administered into the peritoneal cavity are transported to the blood mainly through the lymphatic system, provided that the peritoneum remains intact. If these molecules are toxic to cells they may do considerable damage to body tissues outside the peritoneal cavity such as kidney, liver, lung and bone marrow, and may even be fatal. It is desirable to remove such materials from the blood as quickly as possible. Although the body has natural clearance mechanisms to remove exogenous molecules from the blood circulation, these systems are rather slow for in particular immunoglobulins; leading to a high toxic exposure to the clearing organs such as liver and/or kidney.
Various means to clear the blood from cytotoxic targeting biomolecules (e.g. therapeutic or diagnostic monoclonal antibodies) after i.v. administration have been reported (see review article by Schriber, G. J. and Kerr, D. E., Current Medical Chemistry, 1995, Vol. 2, pp 616-629).
In the so-called avidin chase modality, avidin or streptavidin is administered systemically after administration of the therapeutic or diagnostic antibody to which biotin has been attached, at a time when a sufficient amount of the antibody has been accumulated in the tumor. Avidin or streptavidin will associate with the antibodies and the so formed immunocomplex will clear from the blood circulation via the reticuloendothelial system (RES) and be cleared from the patient via the liver. These procedures will improve the clearance of biotinylated cytotoxic antibodies. An alternative approach to the same end, is the use of anti-idiotypic antibodies. However, all these methods rely on the liver or kidney for blood clearance and thereby expose either or both of these vital organs as well as the urinary bladder to high dose of cytotoxicity. Another major drawback of the methods is the immunogenicity of these agents, particularly the streptavidin, which prevent repetitive treatments once the immune response has been developed.
Extracorporeal techniques for blood clearance are widely used in kidney dialysis, where toxic materials build up in the blood due to a lack of kidney function. Other medical applications where an extracorporeal device can be used include: removal of radioactive materials; removal of toxic levels of metals; removal of toxins produced from bacteria or viruses; removal of toxic levels of drugs, and removal of whole cells (e.g. cancerous cells, specific haematopoietic cellsxe2x80x94e.g. B, T, or NK cells) or removal of bacteria and viruses.
In a preferred embodiment of the invention, a cytotoxic targeting biomolecule (e.g. immunoconjugate) used for therapy of human ovarian cancer is removed from the blood to improve its ratio of target-to-non-target concentration. An improved target-to-non-target ratio provides a better therapeutic index. Specific tissue or organ localization of a biomolecule is a very important factor in its effective application. Lack of specific tissue localization is of particular importance in the treatment with cytotoxic biomolecules, where the desired effect is to kill certain types of cells such as in the treatment of cancer. In order to enhance the specificity, tumor specific monoclonal antibodies are used as a carrier (immunoconjugates) of various cytotoxic moieties, such as, but not limited to, radionuclides, chemotherapy drugs, synthetic or naturally occurring toxins, immunosuppressive agents, immunostimulating agents, and enzymes used in prodrug protocols (Meyer et al., Bioconjugate Chem. 6, 440-446; 1995; Houba et al., Bioconjugate Chem. 7, 606-611, 1996; Blakey et al., Cancer Res. 56, 3287-3292, 1996).
Although tumor-specific immunoconjugates are selectively bound to tumor cells, an initial high concentration of the cell-toxic immunoconjugate in the peritoneal fluid is necessary to reach a sufficiently high concentration in the target tissue. While required for optimal therapy of the cancer, the high concentration of cytotoxic material in the peritoneal fluid will gradually increase the level of the cell toxic material in the blood and other non-tumor tissues, in most cases leading to tissue damage and/or lesion formation in sensitive and vital tissues like the bone marrow. Although, bone marrow rescue is sometimes used to circumvent these potentially lethal effects, such rescue is both extremely costly and poses high risk for the patient.
Even in cases where the bone marrow rescue is effective, other sensitive organs like the liver, kidney, spleen, lung, etc. can be irreparably damaged. The most effective method for preventing tissue and bone marrow damage from toxic materials in blood is to dramatically decrease the amount of that toxic material in the blood. Of course, this must be accomplished in a manner that retains the therapeutic level of toxic material in the tissue being treated (e.g. tumor). Direct transport from the peritoneal fluid to the blood circulation is not considered to be of major significance for most cytotoxic medical agents compared to the lymphatic transportation route. Hence, the concentration of cytotoxic medical agents in the peritoneal fluid is only to a small extent dependent on the concentration of the same medical agent the blood circulation.
Various methods have been proposed to rapidly clear radiolabeled antibodies from blood circulation after the tumor has accumulated a sufficient quantity of immunoconjugate to obtain a diagnosis or therapy. Some of the methods employed involve enhancement of the body""s own clearing mechanism through the formation of immune complexes. Enhanced blood clearance of radiolabeled antibodies can be obtained by using molecules that bind to the therapeutic antibody, such as other monoclonal antibodies directed towards the therapeutic antibody (Klibanov et. al., J. Nucl. Med. 29, 1951-1956, 19888; Marshall et al. Br. J. Cancer 69, 502-507, 1994; Sharkey et al. Bioconjugate Chem. 8, 595-604, 1997), avidin/streptavidin (Sinitsyn et al., J. Nucl. Med. 30, 66-69,1989; Marshall et. al., Br. J. Cancer, 71, 18-24, 1995), or glycosyl containing compounds which are removed by receptors on liver cells (Ashwell and Morell, Adv. Enzymol. 41, 99-128, 1974). Still other methods involve removing the circulating immunoconjugates through extracorporeal methods (see review article by Schriber, G. J. and Kerr, D. E., Current Medical Chemistry, 1995, Vol. 2, pp 616-629).
The extracorporeal techniques used to clear a medical agent from blood circulation are particularly attractive because the toxic material is rapidly removed from the body. Application of these methods in the context of immunotherapy have been previously described (Henry Chemical Abstract, 1991, Vol.18, pp. 565; Hofheinze D et al., Proc. Am. Assoc. Cancer. Res. 1987 Vol. 28, pp 391; Lear J K, et al. Radiology 1991, Vol. 179, pp. 509-512; Johnson T. K. et. al. Antibody Immunoconj. Radiopharm. 1991, Vol. 4, pp. 509; Dienhart D. G., et al. Antibody Immunoconj. Radiopharm. 1991, Vol. 7, pp. 225; DeNardo G. L. et al. J. Nucl. Med. 1993, Vol. 34, pp1020-1027; DeNardo S. J. et. al. J. Nucl. Med. 1992, Vol. 33, pp. 862-863; DeNardo G. L. J. Nucl. Med. 1992, Vol. 33, pp. 863-864; and U.S. Pat. No. 5,474, 772 (Method of treatment with medical agents.).
To make the blood clearance more efficient and to enable processing of whole blood, rather than blood plasma as the above methods refer to, the medical agents (e.g. tumor specific monoclonal antibody carrying cell killing agents or radionuclides for tumor localization) have been biotinylated and cleared by an avidin-based adsorbent on a column matrix. A number of publications provide data showing that this technique is both efficient and practical for the clearance of biotinylated and radionuclide labelled tumor specific antibodies (Norrgren K, et. al. Antibody Immunoconj. Radiopharm. 1991, Vol. 4, pp 54; Norrgren K, et .al. J. Nucl. Med. 1993, Vol. 34, pp. 448-454; Garkavij M, et. al. Acta Oncologica 1996, Vol. 53, pp.309-312; Garkavij M, et. al. J. Nucl Med. 1997, Vol.38, pp.895-901. These techniques are also described in EP0 567 514 (A method and a system for enhanced in vivo clearance of diagnostic and/or therapeutic agents by extracorporeal depletion, and the use of said agents for said purpose). A further development of this method where simultaneous labelling of biotin and radionuclides is described in a patent application by Nilson et al., PCT/SE92/0020 (from which priority is claimed), A Method and a System for Enhanced In Vivo Clearance of Diagnostic and/or Therapeutic Agents by Extracorporeal Depletion, and the Use of said Agents for Said Purpose; and an application by S. Wilbur and B. E. B. Sandberg PCT/SE98/01345, Trifunctional reagent for the conjugation to a biomolecule .
Apart from the prolonged circulation time leading to undesired exposure of toxic immunoconjugate to healthy tissue, inadequate tumor tissue penetration and non-specific organ retention and metabolism contribute to a low therapeutic index ratio. Due to these problems, multi-step antibody-based radionuclide delivery approaches have been extensively investigated. The basic concept involves first the injection of a lesion-specific targeting moiety, which apart from binding specifically to the lesion also has the feature of binding to a subsequently injected radioactive diagnostic agent or a therapeutic agent. By separating these two events one can allow the slow tissue penetrating non-radioactive/non-cytotoxic antibody sufficient time to accumulate in the tumor mass, while the agent carrying the radionuclide/cytotoxin could be selected for more rapid tissue penetration. However, a prerequisite is that the former (and preferably also the later) can be cleared rapidly from the blood circulation.
The so called two and three-step approaches have recently been reviewed in the context of intraperitoneal administration in ovarian cancer therapy (Syrigos K. N. and Epenetos A. A. (2000) Intraperitoneal Radioimmunotherapy of Ovarian Cancer in Radioimmunotherapy of Cancer, eds. P. G. Abrams and A. R. Fritzberg, Marcel Dekker, Inc., New York, p. 315-316).
The present invention relates to improvements in the diagnosis and treatment of peritoneal cancers, including ovarian cancer. The method is based on reducing the level of cytotoxic medical agents or toxic immunoconjugates from the blood circulation, after intraperitoneal injection of these compounds. By depleting the circulating cytotoxic medical agent or immunoconjugate, it is possible both to decrease the toxic side effect on other organs and at the same time increase the therapeutic dose in a single administration or through administration of multiple doses, which results in an increased penetration of the tumor tissue by the cytotoxic medical agent or immunoconjugate.
Thus, in one embodiment, the subject invention comprises a method for improving the treatment of intraperitoneal cancers in mammals comprising: (a) administering a biomolecule intraperitoneally to said mammal; and (b) substantially reducing the level of said biomolecule or a cytotoxic fragment thereof in the blood circulation at suitable time intervals, whereby side effects associated with circulating biomolecule or cytotoxic fragment are reduced. Preferably, the reduction of biomolecule or cytotoxic fragment in the circulation is achieved by passing the blood or a component thereof through an extracorporeal adsorption device. The blood component may be serum or plasma. The extracorporeal device comprises a solid support with a receptor bound thereto; and the biomolecule or cytotoxic fragment is conjugated to an affinity ligand with a high affinity to the receptor. Alternatively, the biomolecule or cytotoxic fragment has a high affinity to the receptor.
The biomolecule can be a cytotoxic medical agent; a cytotoxic medical agent conjugated to a targeting agent; and a targeting agent conjugated to a cytotoxic moiety which is selected from the group consisting of a radionuclide, a chemotherapy drug, a synthetic or naturally occurring toxin, an immunosuppressive, an immunostimulant, and a prodrug activating enzyme. If the biomolecule is the cytotoxic medical agent conjugated to a targeting agent, it is preferred that the affinity ligand be directly covalently bound to the cytotoxic medical agent. If the biomolecule is the targeting agent conjugated to the cytotoxic moiety, it is preferred that the affinity ligand be directly covalently or coordinately bound to the radionuclide or directly covalently bound to the chemotherapy drug, the synthetic or naturally occurring toxin, the immunosuppressive, the immunostimulant, or the prodrug activating enzyme.
The cytotoxic fragment of the biomolecule is a molecule comprising a radionuclide or a toxic metabolite or structure derived from the cytotoxic medical agent, the chemotherapy drug, the synthetic or naturally occurring toxin, the immunosuppressant, the immunostimulant or the prodrug activating enzyme.
In a preferred embodiment, the invention comprises a method for improving the treatment of intraperitoneal cancers in mammals comprising: (a) administering a conjugate of a biomolecule and an affinity ligand intraperitoneally to the mammal; and (b) substantially reducing the level of said biomolecule or cytotoxic fragment thereof in the blood circulation by passing at suitable time intervals the blood or a component thereof through an extracorporeal device comprising a solid support having a receptor bound thereto, the affinity ligand having a high affinity to the receptor, whereby the level of biomolecule or cytotoxic fragment in the circulation is reduced.
The invention also comprises a system for substantially reducing the level of a biomolecule or cytotoxic fragment thereof in a mammal""s blood or component thereof, wherein the biomolecule has been administered intraperitoneally, said system comprising an extracorporeal device having immobilized receptors therein, through which the mammal""s blood or a component thereof is passed, whereby the receptors, which have a high affinity for the biomolecule or the cytotoxic fragment, or for an affinity ligand bound to the biomolecule or the cytotoxic fragment, immobilize the biomolecule or the cytotoxic fragment in the device; means for transporting the blood or blood component to the extracorporeal device; and means for delivering treated blood or blood component from the extracorporeal device to the mammal.
The subject invention further comprises a method for improving the imaging of peritoneal cancers in mammals comprising: (a) administering a conjugate of a radionuclide and a targeting agent intraperitoneally to said mammal, wherein said targeting agent has a high affinity for the cancer; and (b) substantially reducing the level of radionuclide in the blood circulation at suitable time intervals, whereby side effects associated with circulating radionuclide are reduced or whereby imaging contrast is improved. Preferably, the reduction of radionuclide in the circulation is achieved by passing the blood or a component thereof through an extracorporeal adsorption device. The extracorporeal device comprises a solid support with a receptor bound thereto, and the conjugate of radionuclide and targeting agent, or a cytotoxic fragment thereof, is further conjugated to an affinity ligand with a high affinity to the receptor. Alternatively, the receptors in the extracorporeal may have a high affinity to the targeting agent. In a preferred embodiment, a radionuclide is directly covalently or coordinately bound to the affinity ligand, which is directly covalently bound to the targeting agent.
The invention can be illustrated with the simulation exemplified in Example 1. As is explained in Example 1, clinical data from Maraveyas, A. et al. (Cancer 73:1067-1075, 1994) relating to intraperitoneal administration of 90Y-HMFG-1 to patients with ovarian cancer were utilized in the simulation. These data were utilized to simulate the effects of two extracorporeal adsorptions with Mitradep(copyright) (a blood filter having avidin immobilized to agarose particles) conducted at various time after administration of the antibody conjugate. Each adsorption is assumed to remove 90 per cent of the circulating conjugate. It is also assumed that the rate of transport of conjugate from the intraperitoneal volume to blood or the biological half-life of the conjugate in blood is not influenced by the extracorporeal adsorptions. The results illustrated in FIG. 1 illustrate how treatment of the blood at selected time intervals after administration can significantly or substantially reduce the level of biomolecule in the blood, thereby substantially reducing side effects associated with the circulating biomolecule and enhancing the target to non-target ratio for the biomolecule. This improved ratio can result in decreased side effects and/or improved contrast for imaging.
Although the present invention is described for application to human ovarian carcinoma it is also applicable to other types of human cancer diseases where intraperitoneal administration is deemed preferable. The subject procedure is also suitable for the treatment of other mammalian species. The clearance of the biomolecule from the blood is achieved by passing the patient""s whole blood through a device that specifically adsorbs the biomolecule. In the most preferred application, the biomolecule is labelled with biotin and the blood clearance is achieved by passing the blood on-line through a device coated with avidin or streptavidin. Such a device is described in EP0 567514 and exhibits the proper characteristics of the matrix and means of immobilizing the biotin-binding entity for processing of whole blood and obtaining excellent clearance in a reasonable time period. The biocompatibility of an agarose matrix containing immobilized avidin for clinical use has been reported (Bosch, T. et al., Ex Vivo Biocompatibility of Avidin-Agarose: A New Device for Direct Adsorption of Biotinylated Antibodies from Human Whole Blood. Artificial Organs, 2000). It should be stressed that all extracorporeal applications where the patient""s whole blood is processed would also be applicable for the processing of human plasma, although such a system would be both more cumbersome and less efficient.
All references cited herein are incorporated by reference in their entireties.